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Testosterone is a sex hormone. Though it’s primarily associated with the male reproductive system, individuals assigned female at birth also produce testosterone. In people with male reproductive systems, the testes produce testosterone. In people with female reproductive systems, the ovaries and adrenal glands produce testosterone.
Testosterone levels don’t stay the same throughout your lifetime. They fluctuate based on age. Testosterone plays a primary role during male puberty, increasing substantially in males during that time.
In both males and females, testosterone helps maintain a healthy reproductive system, robust libido, and strong bones and muscles throughout life. It’s natural for testosterone levels to decline in both sexes with age.
In people assigned male at birth, testosterone is responsible for the proliferation of male sex characteristics that begin during puberty. This includes increased body hair, muscle development, and the deepening of the voice.
Testosterone is essential in sex drive and sperm production in males. The hormone also affects sex drive in females, as well as the growth and development of muscles, bones, and organs.
Both males and females have similar testosterone levels in childhood. As puberty approaches, testosterone levels rise significantly in people assigned male at birth. In males, these levels tend to peak in adolescence and young adulthood and level out in adulthood.
Testosterone levels begin to gradually decline in males, starting in their 40s and 50s. In females, testosterone levels start declining after the age of 25.
Infancy and Childhood
During infancy and childhood, testosterone levels are low in both males and females. Levels in both sexes are similar from ages 6-10 but higher in males from ages 11-20.
In children assigned female at birth, testosterone concentration starts at about 2.4 nanograms (ng) per deciliter (dL) of blood at age six and increases to about 29.5 ng/dL by age 20. Levels begin to plateau at the age of 14.
In males, testosterone concentration starts at about 1.9 ng/dL at age six. Levels increase to 516 ng/dL by age 20 and plateau around age 17.
Adolescence and Early Adulthood
Adolescence is a time of rapid increases in testosterone in males, coinciding with the onset of male puberty. By a male’s early 20s, their testosterone levels are typically between 409-558 ng/dL, and in the second half of their 20s, between 413-575 ng/dL.
Testosterone levels are fairly even throughout adulthood for females. Certain conditions, such as polycystic ovarian syndrome (PCOS), can cause higher testosterone levels in females.
Adulthood
In adulthood, testosterone levels tend to remain fairly steady in both males and females. In males aged 30-34, testosterone levels average between 359-498 ng/dL. By a male’s mid-30s, testosterone levels are between 352-478 ng/dL. Men in their 40s have testosterone levels between 350-473 ng/dL.
Testosterone plays important roles in reproduction and lipid and glucose metabolism in both males and females. Testosterone levels can also be a factor in disease risk, including the development of chronic diseases like cardiovascular disease, diabetes, metabolic syndrome, and osteoporosis.
Older Age
Testosterone levels decline with age in both males and females. In males, testosterone levels drop by 100 ng/dL every 10 years, starting around age 30. This amounts to a 1-2% drop each year.
Roughly 40% of males aged 45 or older and 50% of males aged 80 or older live with hypoandrogenism, or low testosterone. Symptoms of hypoandrogenism include erectile dysfunction and low libido.
Below is a chart of testosterone levels in males by age:
| Testosterone Levels by Ages, in People Assigned Male at Birth | |
|---|---|
| 6-12 years | 1.9-105 ng/dL |
| 12-18 years | 105-443 ng/dL |
| 20-24 years | 409-558 ng/dL |
| 25-29 years | 413-575 ng/dL |
| 30-34 years | 359-498 ng/dL |
| 35-39 years | 352-478 ng/dL |
| 40-44 years | 350-473 ng/dL |
| 44 and up | declining 1-2% per year |
Abnormal testosterone levels can affect both males and females. Males are more likely to experience symptoms from low testosterone levels, while females are more likely to have negative effects from high testosterone levels.
Abnormal testosterone during puberty can impact the onset and course of male puberty. In males who have finished puberty, low testosterone may be caused by thyroid or testicle issues or chronic diseases like diabetes and cardiovascular disease.
Symptoms of low testosterone in males include:
- Decreased sex drive
- Trouble with erections
- Low sperm count
- Increased breast tissue
- Decreased facial or body hair
- Decreased muscle mass
- Anemia
- Decreased bone mass
High testosterone in females is most often associated with polycystic ovarian syndrome (PCOS). Signs and symptoms of high testosterone in females may include:
- Hair growth on the face and increased hair growth on the rest of the body
- Male pattern hair loss
- Deeper voice
- Difficulty getting pregnant
- Acne
- Irregular periods
Contact your healthcare provider if you have any symptoms of abnormal testosterone levels or if you have concerns about your testosterone levels.
If you are showing signs of abnormal testosterone levels, your provider will likely perform a blood test to measure your testosterone levels. Testosterone is usually highest in the morning, between 7 a.m. and 10 a.m., so your provider may ask you to come in for testing then.
Several forms of testosterone may be tested, including:
- Total testosterone: This includes free testosterone and testosterone attached to proteins
- Free testosterone: This measures testosterone not attached to proteins
- Bioavailable testosterone: This measures testosterone attached to the protein albumin
If you have abnormal testosterone levels, you should talk to your healthcare provider about the best treatment options for you. Treatment often involves a combination of lifestyle changes and medication.
Certain health conditions and lifestyle habits are linked with low testosterone levels in males. Males who have diabetes, smoke, are physically inactive, and carry excess weight are more likely to have low testosterone.
Taking steps like eating a nutritious diet, exercising, and avoiding or quitting smoking can help improve your testosterone levels. These habits can also reduce your risk of or help manage health conditions like type 2 diabetes and obesity.
For males, testosterone therapy may help treat lower-than-normal testosterone levels. However, there’s inconsistent evidence on the benefits of testosterone therapy for aging-related declines in testosterone. Some evidence also shows testosterone therapy may increase your risk of cardiovascular issues. Discuss the pros and cons with your physician.
For people assigned female at birth, high testosterone levels associated with PCOS are often treated by managing insulin resistance, increasing exercise, maintaining a healthy weight, taking hormonal birth control, and taking anti-androgen medication.
Testosterone is a sex hormone that both males and females produce. It tends to be lower in childhood. During male puberty, testosterone spikes and remains higher than female testosterone levels throughout the lifetime. Testosterone decreases in both males and females as they age.
In males, low testosterone is associated with late puberty, erectile dysfunction, and low libido. In females, high testosterone is associated with conditions like PCOS.
If you have questions or concerns about your testosterone levels, you should see your healthcare provider. They can perform blood tests to measure your testosterone levels and discuss treatment plans.
